The following disclosure relates to a vehicle-height control system configured to control a vehicle height by controlling supply and discharge of fluid in a vehicle-height control actuator.
Patent Document 1 (Japanese Patent Application Publication No. 3-70615) discloses a vehicle-height control system including: a tank 22; an air-discharge valve 34; a passage L1 connected to the tank 22; an electromagnetic valve 21 provided on the passage L1; a passage L2 connected to the air-discharge valve 34; an electromagnetic valve 32 provided on the passage L2; and air spring devices 11-14 connected to the passage L1 and the passage L2 respectively via vehicle-height control valves 15-18. In this vehicle-height control system, in the case where up control for increasing a vehicle height is executed, the electromagnetic valve 21 and one or ones of the vehicle-height control valves 15-18 which correspond to control target wheels (e.g., the vehicle-height control valve 15 in this explanation) are opened (at S216 in FIG. 3 in Patent Document 1). In the case where down control for lowering the vehicle height is executed, the air-discharge valve 34, the electromagnetic valve 32, and the vehicle-height control valve 15 are opened (at S402 in FIG. 5 in Patent Document 1).